Process for preparing an aqueous adhesive composition

Abstract

A process for preparing an aqueous adhesive composition which comprises preparing a solvent dispersion by mixing rubber, carbon black, vulcanizing agent, tackifying resin and accelerator with sufficient organic solvent to form a solvent dispersion and thereafter emulsifying the solvent dispersion in the presence of water to form an aqueous emulsion. The aqueous emulsion may be used to bond unvulcanized rubber compounds, such as a tread stock to the carcass portion during the formation of a tire.

What is claimed is: 
     
       1. A process for preparing an aqueous adhesive composition for bonding unvulcanized rubber compounds together which comprises dispersing a premilled mixture containing rubber selected from the group consisting of natural rubber, synthetic rubber and mixtures thereof, a rubber reinforcing agent in an amount of from about 10 to 40 parts by weight per 100 parts by weight of rubber, a vulcanizing agent in an amount of from about 1 to about 8 parts by weight per 100 parts by weight of rubber, said vulcanizing agent is selected from the group consisting of sulfur, sulfur containing compounds, organic peroxides, metallic oxides, selenium and tellurium and an accelerator that is compatible with the mixture and is selected from the group consisting of mono- and di-sulfides, thiocarbamates, sulfenamides, thiazoles, quanidines, fatty acids having from 10 to 22 carbon atoms and oxides of zinc and magnesium with up to about 600 parts by weight per 100 parts by weight of rubber of an organic solvent for the rubber, said organic solvent is selected from the group consisting of aliphatic hydrocarbons, cyclic hydrocarbons, aromatic hydrocarbons, naphtha and chlorinated hydrocarbons and from about 5 to 70 parts by weight per 100 parts by weight of rubber of a tackifying resin which is soluble in the organic solvent to form a solvent dispersion and thereafter emulsifying the solvent dispersion in the presence of water and sufficient emulsifying agent to form a stable emulsion, said emulsifying agent is selected from the group consisting of anionic, cationic and non-ionic emulsifying agents and mixtures thereof to form an aqueous emulsion. 
     
     
       2. The process of claim 1, wherein the rubber is natural rubber. 
     
     
       3. The process of claim 1, wherein the rubber is a mixture of natural rubber and synthetic rubber. 
     
     
       4. The process of claim 1, wherein the tackifying resin is added after the rubber, reinforcing agent, vulcanizing agent and accelerator are added to the organic solvent. 
     
     
       5. The process of claim 1, wherein the tackifying resin is dissolved in the solvent prior to the addition of the rubber, reinforcing agent, vulcanizing agent and accelerator. 
     
     
       6. The process of claim 1, wherein the amount of solvent is from 300 to 600 parts by weight per 100 parts by weight of rubber. 
     
     
       7. A process for preparing an aqueous adhesive composition for bonding unvulcanized rubber compounds together which comprises milling a mixture containing rubber selected from the group consisting of natural rubber, synthetic rubber and mixtures thereof, carbon black, a vulcanizing agent in an amount of from about 1 to 8 parts by weight per 100 parts by weight of rubber, said vulcanizing agent is selected from the group consisting of sulfur, sulfur containing compounds, organic peroxides, metallic oxides, selenium and tellurium and an accelerator that is compatible with the mixture which is selected from the group consisting of mono- and di-sulfides, thiocarbamates, sulfenamides, thiazoles, quanidines, fatty acids having from 10 to 20 carbon atoms and oxides of zinc and magnesium at a temperature up to about 80° C. to form a rubber compound, mixing up to about 600 parts by weight per 100 parts by weight of rubber of an organic solvent for the rubber with the milled mixture, said organic solvent is selected from the group consisting of aliphatic hydrocarbons, cyclic hydrocarbons, aromatic hydrocarbons, naphtha and chlorinated hydrocarbons and from about 5 to 70 parts by weight per 100 parts by weight of rubber of a tackifying resin which is soluble in the organic solvent to form a solvent dispersion and thereafter emulsifying the solvent dispersion in the presence of water and sufficient emulsifying agent to form a stable emulsion, said emulsifying agent is selected from the group consisting of anionic, cationic and nonionic emulsifying agents and mixtures thereof to form an aqueous emulsion. 
     
     
       8. The process of claim 7, wherein the emulsifying agent is an anionic emulsifying agent selected from the group consisting of sulfonated dodecylbenzene, sodium salts of dodecylbenzenesulfonate and derivatives thereof. 
     
     
       9. The composition obtained from the process of claim 1. 
     
     
       10. The process of claim 1, wherein the tackifying resin is selected from the group consisting of indene resins, rosins, coumarone resins, oil-soluble phenolic resins, coumarone-indene resins, rosin-polyterpene resins, glycerol esters of hydrogenated rosins, pentaerythritol esters of hydrogenated rosin, hydrogenated rosin, glycerol esters of polymerized rosin, maleic anhydride-modified rosin, rosin derivatives, partial esters of styrene-maleic acid copolymers and chlorinated biphenyls. 
     
     
       11. The process of claim 1, wherein the accelerator is selected from the group consisting of thiuram disulfide, selenium diethyldithiocarbamate, zinc dibutyldithiocarbamate, zinc diethyldithiocarbamate, zinc dimethyldithiocarbamate, zinc 2,2'-dithiobisbenzothiazole, tetramethylthiuram monosulfide, diphenylquanidine, N-cyclohexyl-2-benzothiazole sulfenamide, N-tert-butyl-2-benzothiazole sulfenamide, 2-mercaptobenzothiazole and benzothiazyl disulfide.